Recently, several new fabrics have begun challenging Gore-Tex. You probably noticed. The siege on the brand that literally built the waterproof-breathable outdoor gear market, and was enjoying a peaceful 30-year dictatorship over it, hasn't been covert. The gloves, at last, are off.

Of course, other waterproof-breathable fabrics emerged over the years (Patagonia's H2No, Marmot's MemBrain...) but none claimed to be BETTER than Gore-Tex. Until the 'eVent'ful (sorry...) year of 1999, when a new fabric was widely acclaimed as more breathable. Gore-Tex weathered that storm, but the flood gates seemed to open, and Polartec emerged as a conspicuous and powerful contender. Has anyone escaped being eyeballed by their unnerving marketing pictures over the last year: haggard-looking climbers, now 'liberated by NeoShell'?

The Fabric: Polartec NeoShell

NeoShell, Polartec claim, is 99.9% windproof, stretchy, warm without weight, less noisy than a hard shell and five times more breathable than 'the leading waterproof-breathable'. Too good to be true? Should Polartec retreat to synthetic fleece manufacture, or are they onto something?

Some background: NeoShell follows Polartec's successful foray into really water resistant soft shell with Powershield Pro in 2010. Sort of soft shell, sort of hard shell, NeoShell is a new shell concept. For me, the fabric has its own place in the market and doesn't need to war with Gore-Tex.

Like Gore-Tex, this new fabric has a waterproof-breathable membrane (polyurethane rather than Gore's ePFTE). However, it has a lower Hydrostatic Head (measure of waterproofing), and I found it more breathable than Gore-Tex Pro, Performance Shell (or eVent, actually). Gear manufacturers have been making both soft shell and hard shell style products from NeoShell, and outdoor enthusiasts have enjoyed it for everything from slow energy hillwalking to high energy cross country skiing. As a fabric weight comparison, the women's Rab Stretch Neo is 480g; the women's Arc'teryx Alpha SV Gore-Tex Pro jacket 486g. The Rab Stretch Neo is lighter on the pocket though: £250.

"Too good to be true? Should Polartec retreat to fleece manufacture, or are they onto something?..."

Waterproofing

Hydrostatic Head varies depending on face fabric. Gore don't seem to publicise theirs, instead they offer the 'Guaranteed To Keep You Dry' promise. I believe Gore-Tex Pro Shell has a H/H of around 28,000 (withstands a water column of 28m); Active Shell 18,000. Polartec have been very open about NeoShell's 10,000 H/H waterproofing (Rab tell me this is very much a minimum figure). Polartec's take is that 10,000 is plenty, any more compromises breathability. At first I was dubious but, over six months of regular use, I've been persuaded to agree. Everything from the most minging downpours Wales can muster to hurling snow and sleet on Scottish summits has stayed firmly outside the fabric, and I found no drips or damp patches on my midlayers.

Pleasant testing conditions in the Cairmgorms

Breathability

Sweat has never built up enough to dampen my midlayer, either. I found the interior climate very comparable to soft shell, and understand Marmot's decision to classify NeoShell as heavy duty soft shell rather than hard shell. Previously I've avoided a hard shell unless it's wet or I wanted the added wind protection, but this autumn and winter I continually wore a light down/synthetic midlayer, zipped the NeoShell over, and walked, skied or climbed all day. While others wrestled layers on and off, I remained absolutely happy in this system, unless I stopped for long, in which case I added a down layer.

Windproofing

NeoShell works, apparently, using 'a dynamic two way air exchange'. Air can pass out carrying moisture, so sweat can move out as soon as you start sweating, whereas sweat needs to become vapour to get through Gore-Tex. Can fabric be windproof and air permeable at the same time, though? The claim that NeoShell is 99% windproof seemed OTT to me. I found strong summit winds got through my Rab Neo Stretch. Not as much as through soft shell but I didn't find an almost impenetrable barrier like Gore-Tex. Toby found his Marmot Zion very windproof though (apparently the Neo Stretch uses a lighter weight of NeoShell). I was happy to put up with a bit of wind chill in return for the breathability.

Summary

I've reached for the Rab Stretch Neo far more than any other hard or soft shell this autumn/winter (apart from a lighter weight shell for running). I'm a definite Polartec NeoShell fan.

Michael Cattanach, waterproof specialist at Polartec and Global Business Manager by title, comments:

I realise that it's not our business to influence or bias reviews, only to get the best products out there that we possibly can. Your point about the wind resistance is an interesting one though, I'd love to hear more of your experiences as you – hopefully – continue to use the NeoShell garment. Our experience so far is that users are employing NeoShell in many different ways – we're hearing everything from endurance racing to cross-country skiing, activities where a traditional hardshell would not be an option – and subsequently learning to layer differently to get the most out of the NeoShell performance.

Thanks again, I loved seeing the pictures of the testing in the Cairngorms, makes me homesick for abjectly foul weather. People here don't believe me when I say Scotland is the toughest test environment on the planet, where else can you get the full force of the Atlantic below 3000 feet?

The Jacket: Rab Stretch Neo

Available colours in the Rab Stretch NeoShell. Mens on the left, Womens on the right

First impressions

I love the bright colours Rab go for, and this turquoise has led to many compliments, and jacket disappearances - I've had to remember who's borrowed and walked off with it this time. As for design and specification, I was interested to read Toby's review of the Marmot Zion (also made from NeoShell); while Marmot have created a soft shell style jacket from the fabric, Rab have crafted very much a typical hard shell. The fabric feels a bit softer than Gore-Tex Pro Shell, but a similar weight. This jacket is 480g; for comparison the Arc'teryx Alpha SV Gore-Tex Pro jacket is 486g. The fabric feels and looks somewhere between soft shell and hard shell.

Sarah Stirling and Bridget Collier on the summit of Cribyn, Brecon Beacons NP

Big up to Rab's women designers: I found the fit artfully shaped to my body without restricting it. I'm usually a size 8, and I bought a size Small, which allows me to fit a synthetic or lightweight down puff under it. The generous length covers my bum, and the drawcord hem cinches in typical hard shell style. Both features helped keep me warmer on the jacket's first outing: climbing at Godnor South on Portland while wind whipped the cliff. I found plenty of movement in the arms, and the jacket has some stretch, so it didn't lift out of my harness much. The sleeves are nice and long - I can tuck my hands in for belaying - and I like the cuffs, which adjust with dainty rubberised Velcro tabs. These proved easy to grab, even with big gloves and numb fingers in Scottish winter, and slip easily under gloves.

Hood

The hood (see below) has a wired peak. I prefer these to laminate; you can adjust the shape to keep out weather without restricting your view. The hood easily swallows a helmet and feels a bit spacious without one (see top picture). A rear toggle pulls it off your face, working well in the usual way to enhance peripheral vision. In a white out you can undo this toggle and cinch to balaclava-style using two front drawcords. The toggles for these run through two fabric channels either side of your face. I'd prefer their ends were inside the jacket, rather than outside and ended in plastic grippy bits, which can twang into your cold face! The high neck on this jacket effectively and comfortably adds to the cosy balaclava effect. On other Rab shells I've found the high neck annoying, as the hard fabric rubs my face, but NeoShell is softer.

The front YKK Aquaguard zip is further protected by an internal storm flap. This combination has proved watertight - so far I've never found any drips or wet patches on my midlayer. The zip's water resistant outer coating looks and feels like silicon. Its tiny teeth can occasionally prove 'sticky' on this rubbery surface, especially in cold weather (or maybe it's my cold hands!) On other jackets Rab have been using the Vislon Watertight Zip (which Arc'teryx also use); I prefer its better durability and smoother sliding.

Pockets

The two front chest pockets easily swallow maps and guidebooks. They are the size of the dark colour fabric on the front of the jacket (see photo of jacket range above) - as far as the side seam - so pretty big. I've noticed the wind doesn't get through the front as much as through the back, as the extra layer of fabric improves wind protection. However, as people have commented in the forums, they are Napoleon pockets rather than handwarmers, so you'll have to snuggle your paws elsewhere. Since I usually have mine out in gloves or pulled up into my sleeves, I've not found this an issue.